The present invention relates to devices used in the surgical arts to fix the positional relationship of vertebrae of the spine, and more particularly to a pedicle screw and rod assembly for this purpose. There are various prior art devices available, which are intended for fixing the positional relationship of the vertebrae of the spine. For example, when attempting to achieve osteosynthesis, the specific fusion of different segments of the spine, one has to provide some type of immobilization. The current different systems typically involve placement of screws into the pedicle region of the vertebrae, which are then connected to each other by use of various sizes of rods, plates, or wires. However, these methods and devices for the fusion of vertebrae are not always appropriate when immobilization to promote fusion is not intended. Therefore, it would be beneficial to have a system with a somewhat flexible means of interconnecting the pedicle screws, and which would allow adjustment of the tension between at least two interconnected pedicle screws where the intent is to avoid fusion of the subject vertebrae.
Spinal degeneration results in the loss of height between the vertebrae. This loss in height usually results in the pinching of a nerve which routes through the vertebrae, hence causing pain. In these cases it is often desirable to restore the spacing between the vertebrae rather than to fuse them. It would be additionally beneficial to have a device that would maintain the surgically restored resting height of the vertebrae, while allowing some flexion, extension and compression of those vertebrae relative to each other. Further, in view of the large number of pedicle screws available in the osteosynthesis field, it would be especially beneficial to have a device that accomplishes these objectives when combined or used with an existing type of osteosynthesis pedicle screw.